package com.ssy.lingxi.system.utils;

import java.io.*;
import java.net.MalformedURLException;
import java.net.URL;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Base64;

/**
 * 文件MD5加密
 * @author hzh
 */
public class FileMd5Utils {

    /**
     * 默认的密码字符串组合，用来将字节转换成 16 进制表示的字符
     */
    private static char hexDigits[] = { '0', '1', '2', '3', '4', '5', '6','7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' };
    private static MessageDigest messagedigest = null;
    static {
        try {
            messagedigest = MessageDigest.getInstance("MD5");
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        }
    }

    public static String getFileMD5String(File file) throws IOException {
        InputStream fis;
        fis = new FileInputStream(file);
        byte[] buffer = new byte[1024];
        int numRead = 0;
        while ((numRead = fis.read(buffer)) > 0) {
            messagedigest.update(buffer, 0, numRead);
        }
        fis.close();
        return bufferToHex(messagedigest.digest());
    }

    public static String getStringMD5(String str){
        byte[] buffer=str.getBytes();
        messagedigest.update(buffer);
        return bufferToHex(messagedigest.digest());
    }

    public static String bufferToHex(byte bytes[]) {
        return bufferToHex(bytes, 0, bytes.length);
    }

    private static String bufferToHex(byte bytes[], int m, int n) {
        StringBuffer stringbuffer = new StringBuffer(2 * n);
        int k = m + n;
        for (int l = m; l < k; l++) {
            appendHexPair(bytes[l], stringbuffer);
        }
        return stringbuffer.toString();
    }

    private static void appendHexPair(byte bt, StringBuffer stringbuffer) {
        char c0 = hexDigits[(bt & 0xf0) >> 4];// 取字节中高 4 位的数字转换
        // 为逻辑右移，将符号位一起右移,此处未发现两种符号有何不同
        char c1 = hexDigits[bt & 0xf];// 取字节中低 4 位的数字转换
        stringbuffer.append(c0);
        stringbuffer.append(c1);
    }

    /**
     * 图片可访问的网络地址
     * 如：http://app.chachastation.com/uploadIMG/public/20170920161849653928.png
     * @param URLName
     * @return
     */
    public static String getMD5(String URLName){
        String name="";
        try {
            URL url = new URL(URLName);
            InputStream inputStream = new BufferedInputStream(url.openStream());
            byte[] bytes = new byte[1024];
            int len = 0;
            MessageDigest messagedigest = MessageDigest.getInstance("MD5");
            while ((len = inputStream.read(bytes)) > 0) {
                messagedigest.update(bytes, 0, len);
            }
            name = bufferToHex(messagedigest.digest());
            inputStream.close();
        } catch (MalformedURLException e) {
//            LogUtil.getLogger().warn(e);
        } catch (IOException e) {
//            LogUtil.getLogger().warn(e);
        } catch (NoSuchAlgorithmException e) {
//            LogUtil.getLogger().warn(e);
        }
        return name;
    }


    /**
     * 通用加密方法
     * @param str     需要加密的字符串
     * @param isUpper 字母大小写(false为小写，true为大写)
     * @param bit     加密的位数（16,32,64）
     * @return
     */
    public static String getMD5(String str, boolean isUpper, Integer bit) {
        String md5 = null;
        try {
            // 创建加密对象
            MessageDigest md = MessageDigest.getInstance("md5");
            if (bit == 64) {

                //改成使用java.util.Base64
                md5 = Base64.getEncoder().encodeToString(md.digest(str.getBytes("utf-8")));

//                BASE64Encoder bw = new BASE64Encoder();
//                md5 = bw.encode(md.digest(str.getBytes("utf-8")));
            } else {
                // 计算MD5函数
                md.update(str.getBytes());
                byte b[] = md.digest();
                int i;
                StringBuilder sb = new StringBuilder();
                for (byte aB : b) {
                    i = aB;
                    if (i < 0) {
                        i += 256;
                    }
                    if (i < 16) {
                        sb.append("0");
                    }
                    sb.append(Integer.toHexString(i));
                }
                md5 = sb.toString();
                if (bit == 16) {
                    //截取32位md5为16位
                    md5 = md5.substring(8, 24);
                    if (isUpper) {
                        md5 = md5.toUpperCase();
                    }
                    return md5;
                }
            }
            //转换成大写
            if (isUpper) {
                md5 = md5.toUpperCase();
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        return md5;
    }
}